<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>结构伪类选择器-基本使用</title>
  <style>
    li:first-child {
      color: red;
    }
    li:nth-child(3){
      color: blue;
    }
    li:last-child{
      color: green;
    }
  </style>
</head>
<body>
  <ul>
    <li>li 1</li>
    <li>li 2</li>
    <li>li 3</li>
    <li>li 4</li>
    <li>li 5</li>
    <li>li 6</li>
    <li>li 7</li>
    <li>li 8</li>
  </ul>
</body>
</html>